TW483919B - Polyoxymethylene compositions and its reparation method and uses - Google Patents

Abstract

A composition with improved set-up time and reduce shrinkage, comprising: (a) a polyoxymethylene polymer; (b) a polyalkylene/unsaturated carboxylic acid lower alkyl ester polymeric nucleating material; (c) a waxy denucleating material; and (d) a nucleant.

Description

V. Description of the invention (l) '' --- ---- ijj BACKGROUND The present invention relates to a polyacetal (also referred to herein as polyacetal) with improved molding ) Resin composition. Taken, the shrinkage resin is obtained from most of the brewing monomers or the trimer terpolymers (Miyazaki). The acetal homopolymer is a homopolymer of acetal (for example, manufactured by Ε · 丨 · du 〇〇orU de Nemours company, and has a single price, 丄,% private total plus a 衣 —clothing n #Finebismuth resin). The acetal copolymer is obtained by copolymerizing, for example, oxyoxane and, for example, trioxane. Fatigue resistance for automotive applications Poly: Nagumi is widely used in, for example, electrical and electronic applications and precision machinery applications due to its high mechanical strength, excellent friction resistance, and nature-saving characteristics. Polyacrylic acid resin is the most crystalline of the work shoes | θ middle plate% ^ compound and therefore frozen in the mold #, k ... However, these resins are also highly shrinkable. Recently, the nucleated polyfluorinated resin has been improved to improve upon the improvement, especially for the improvement, especially Li 2 ;;: reduce the shrinkage. However, there is still a need to substantially eliminate voids in the molded article. And 4C or sound, summary J hair, including a kind of polymethyl methacrylate resin and polyalkyl ester polymerized nucleation material, a clear target ^ carboxyl low stone blend. The combination of these two chemical substances and nucleating agents elongs; it also has a good set time and reduces sensitivity and improvement. In addition to the above, Xiao ^,% ° M thermal deformation. The use of this composition can eliminate or remove only 4 voids in molded articles :: Additives, that is, elongation-based (meth) propylene ::: ,,, Ethyl methacrylate g-methyl ester (EMA) , Wax removal, V-form nucleating agents such as gas between talc, f to 4, cutting nucleating materials such as polyethylene wax and < unknown synergy between the description.

O: \ 56 \ 56383.PTD

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V. Description of the invention (2) Brief description of the diagrams Figures 1a and 1b show the crystallization time 1/2 time map to various polycarboxylate inclusions. ^ Figures 2a, 2b, and 2c show photocopy reproductions of cut-away sections of rod-shaped rots from the jujube tree with various additives. 'Figures 3a and 3b show photocopy reproductions of cut surfaces of molded articles molded from polyacetal resins containing various additives. Figures 4a and 4b show photocopy reproductions of cut surfaces of rod-shaped objects molded from poly-Jun resins containing various additives. DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composition 'comprising a polyoxymethylene resin and a combination comprising the following components: a) polyalkylene / unsaturated carboxylic acid low-carbon burnt ester polymerization nucleation substance; b) waxy enucleation Chemical substances; and c) nucleating agents. In detail, the composition contains a polyoxymethylene resin and a combination including the following components: a) 0. 5 to 3 wt% of a polysexen / unsaturated carboxylic acid low-carbon alkyl ester polymerization nucleation material; M0 · 1 to 1 wt% waxy funnel nucleating substance; and 0.01 to 3 wt% nucleating agent. A preferred composition contains a polymethyl resin and a combination comprising the following components: a) 1 to 3 wt% of an ester nucleating substance; b) 0.1 to 1 wt% of a waxy denucleating substance; and

苐 Page 5 483919 V. Description of the invention (3) c) 〇 · 〇 1 to 3 wt% of nucleating agent. It is understood that the percentage of weight s is based on the total composition. The rest of the composition is made up of Poly-Jun resin and other additives. The resin used in Ben Sheming contains a wide variety of homogeneous resins and copolymers known in the art. These polymers are general formazan polymers in which the polymer chain (except the end of the chain) is a series of methyl and oxygen bonds. This polymer chain may also include the following general formula: R1-(C) m-foot 2 /, where m is an integer from 1 to 5 and | ^ and | ^ are inert substituents that do not cause adverse reactions in the polymer . Such additional components of the polymer chain are present in small proportions of repeating units. The component of 'π polyformaldehyde resin used herein' includes a homopolymer of formaldehyde or a cyclic oligomer of Jun, whose end groups are terminated by esterification or etherification; and a Jun or formaldehyde cyclic oligomer A copolymer of a polymer and other monomers which can generate an oxyalkylene group having at least two adjacent disk atoms in the main chain, and the end group of the copolymer may be a base end or may be terminated by esterification or etherification The polyacetaldehyde used in the present invention may be a linear chain or a substantially fenced bond with only a small number of branches and usually has a weight average molecular weight in the range of 40,000 to 175,000, and preferably contains 50,000 to 5,000. 1 50, 0 0 〇. It is preferred that the polyoxymethylene resin does not have a measurable amount of branching. The molecular weight can be conveniently measured by gel permeation chromatography (C) or hexafluorophenol at room temperature. Measured in isopropanol. Although depending on the properties and processing properties, a higher or lower weight average molecular weight 111A light resin can be used, but polyacetic acid with the aforementioned weight average molecular weight is referred to as Λ < To provide melt blending to the desired combination of physical properties

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Amendment No. 88100066 V. Description of the Invention (4) The best balance of the good mixing of the various ingredients in the composition with the ingredients made from such a composition. As described above, the polyacetal resin may be a homopolymer having a different weight average molecular weight, a copolymer having a different weight average molecular weight, or a mixture thereof. The copolymer may contain one or more comonomers, such as those commonly used in the manufacture of polyacid compositions. More commonly used comonomers include alkylene oxides of 2 to 12 carbon atoms and their cyclic addition products with formaldehyde. The amount of comonomer is not more than 20% by weight, preferably not more than 15% by weight, and most preferably about 2% by weight. Common comonomers include ethylene oxide, dioxolane, and butylene oxide. In general, polyacetal homopolymers are better than copolymers because of their higher tensile strength and stiffness. Preferred polyacetal homopolymers include those whose hydroxyl end groups have been blocked by a chemical reaction to form an ester or ether group, preferably acetate or methoxy, respectively. Polynuclear alkylene / unsaturated carboxylic acid lower alkyl ester polymerized nucleating materials are usually copolymers or trimers of lower carbon number (C2-C4) alkylene and unsaturated acid lower alkyl esters. An example of a polymeric nucleating substance which can be used in the present invention is an ethylene-based polymer of the formula E / X / Y, preferably E / X. In the formula E / X, E is ethylene and X is an unsaturated carboxylic acid ester. The unsaturated carboxylic acid ester contains an unsaturated carboxylic acid alkyl ester (C ^ -Cs, preferably C4) having 3 to 8 carbon atoms. Exemplary unsaturated acids include acrylic acid and methacrylic acid. Specific examples of esters are ethyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, ethyl methacrylate, ethyl ethyl acrylate, ethyl propyl acrylate, ethyl isopropyl acrylate Esters, n-butyl fluorenyl acrylate and isobutyl fluorenyl acrylate, of which ethyl acrylate and methyl methacrylate are preferred.

O: \ 56V56383.ptc Page 7 2001.08. 03.007 483919 V. Description of the invention (5) ------- ^ Good ^ Dilute dienoic acid methyl ester copolymer (π EMA ") components are usually negative for commercial products It can be prepared by known methods. The amount of methyl acrylate in the EMA is usually 3 to 40% by weight of EMt, preferably 15 to 25% by weight. 1. Poly-elongated / unsaturated slow-acid low-carbon alkyl ester nucleating additives can also be ethylene-based random polymers of formula E / X / Y, where e is ethylene and χ is selected from methyl propylene Acid methyl ester, ethyl acrylate and butyl acrylate, and fluorene are selected from glycidyl methacrylate and glycidyl acrylate, and γ is preferably glycidyl acrylate. E / χ / γ is mainly composed of 5-99% of E, 0 ~ 35% of X, and 0.5-10% of γ. Examples of ethylene-based random polymers are mainly composed of 90 to 99% by weight of ethylene: and 110 gram of glycidyl methacrylate. Preferably, the ethylene / methacrylic acid glycidyl ester (" EGMA ") random polymer is mainly composed of 90-97% by weight of ethylene and 3-0% by weight of methacrylic acid glycidyl ( " GMA "). Another preferred random polymer mainly composed of ethylene is mainly composed of 60-985% by weight of ethylene, 0.5-35% by weight of butyl acrylate (,, BA ") and 10-10% by weight = Glycidyl acrylate (" GMA "). Preferably, this ethylene / butyl acrylate / glycidyl methacrylate (,, EBAGMAn) random polymer is mainly composed of 5 to 84% by weight. Ethylene, 15-35% by weight ^ and bu 10 weight; \ of GMA. Better, this EBAGMA is mainly composed of 57.5-74% by weight ^ dilute, 2 5-3 5% by weight iBA and 丨- 7.5% by weight of iGMA. ^ It is mainly ethylene! The polymer component can be obtained by techniques known in the art: Examples of EgAGMA random polymer are provided at usp. 4,75 3. Wax negative denuclearization component Dispersible in polyacetal resin and at normal room temperature

483919 V. Description of the Invention (6) Liquid substances. Alternatively, if the substance is solid at normal room temperature, it needs to be fluidized at a temperature below the polyacetal processing or molding temperature. Examples of useful waxy desalination components are natural or synthetic waxes, such as hydrocarbons and polymeric waxes. Hydrocarbon waxes include ceresin, petroleum wax, paraffin or microcrystalline wax, and synthetic waxes, such as ethylene-based polymers or chlorinated zeolites. Polymeric waxes include polyethylene, polypropylene, and ethylene / propylene copolymers. Preferred materials include rocky soil and polyethylene. Good blending can be achieved if the ingredients are mixed together in a biaxial extruder, which is the preferred mixing device. The nucleating agent useful in the present invention is any fine-grained solid, such as boron nitride, talc, silica, polyimide, branched or cross-linked acetal copolymer or terpolymer, melamine-formaldehyde resin, calcium carbonate, Diatomaceous earth, dolomite, or other known nucleating agents used for polymerization. Boron nitride, trimer or talc is preferred, and branched trimer is most preferred. Nucleating agents can be surface-treated in standard processes as required. The branched or crosslinked poly (oxymethyl) group used as a nucleating agent in the present invention can be prepared as follows. a. Trioxane is copolymerized with at least one compound that is reactive with trioxane polyfunctionality and copolymerized and optionally with at least one compound that is reactive with trioxane monofunctionality and copolymerized, or b. subsequently Branching or cross-linking with a linear poly (oxyalkylene) functional group with a side chain or chain bond, or c. Allowing trioxane to react with and copolymerize with at least one trifunctional monofunctional The compound is copolymerized with a branched or crosslinked polyether, or a linear poly (oxymethylene group) is reacted with the branched or crosslinked polyether.

Page 9 V. Description of the invention (7) The nucleating agent preferably has a smaller ratio than 2. Micron is preferably smaller than!. Micro] pull: most:,; The average particle size needs to be small. The nucleating agent can be the encapsulating nucleation zibbon == a few meters. Consists of an encapsulant polymer and a nucleating agent. The main nucleating agent, the encapsulant polymer can be melted at any moderate melting nucleating agent polyacetal resin at the processing temperature: 2: 1 means that the encapsulating polymer contains linear low-density polyhexene ^组合。 The compound. Exemplified polyethylene (" HDPE ") and polypropylene, each with E"), high density solid density (measured by ASTM D1 5 0 5). _, No; spoon or equal to 1 g / cm3 of one of LLDPE or HDPE. The polymer of the encapsulant is a long-chain polymer branch or mainly a straight-chain polymer. The lack of '/ Height% structure may lack the method of encapsulant polymer. , ~ Knife is because the manufacture of the encapsulant polymer is selected from the polymer known in the art can be purchased commercially or can be borrowed from the arts; the lane package smart polymer sealant polymer is made of ethylene or ethylene and "_ Preparation of olefins. It is prepared in a gas-phase reactor using coordination catalysts, especially homogeneous, solution-phase or fine UUP catalysts. It is preferred that the molten private number (measured under ASTM D1 2 38 Method Condition E) be within the range of 5 to 55 g / 10 minutes fc. Preferred HDPE encapsulant polymers have a melt index (measured under A STM D 1 2 38 method condition e) in the range of about 0.5 to 7 g / 10 minutes. Compositions with a melting index outside of the above range iLLDpE * HDpE can produce material shapes with good porosity values, but improve the shape of compound resins and extruded materials with other undesired properties, such as reducing polyacid and LLDPE Or the stability of HDPE or separation (ie delamination).

Page 10 483919 V. Description of the invention (8) It is necessary to avoid additives or ingredients that have an adverse effect on the oxidation or thermal stability of polyacetal. In addition to the aforementioned ingredients, the composition of the present invention may include other ingredients, modifiers, and additives generally used in polyacetal compositions, including heat stabilizers and co-stabilizers, antioxidants, colorants (including pigments), Welding agents (such as thermoplastic polyurethanes), reinforcing agents, ultraviolet light stabilizers (benzotriazole or dibenzone), containing hindered amine light stabilizers (especially where the blocked nitrogen is tertiary Those with amine functionality or those in which the hindered amine light stabilizers contain hexahydropyridine or hexahydropyridone and the three-field ring), glass and filler. Suitable thermal stabilizers include polyamides (including nylon 6 6, nylon 6/10, and nylon terpolymers of nylon 6 and polyamide stabilizers of USP 3, 96, 984); meltable The hydroxyl-containing polymers and copolymers include ethylene vinyl alcohol copolymers and stabilizers described in USP 4,8 1 4,3 9 7 and USP 4,7 6 6,168; described in USP 5,0 1 1, 8 9 0 non-meltable hydroxyl- or nitrogen-containing polymers and especially polypropylene fluoramide; and microcrystalline cellulose; poly / 5 aniline (as described in German published application 3715 117); polypropylene 醯Amines; or stabilizers disclosed in USP 4,814, 397; 4, 766, 168; 4, 64 0, 949 and 4, 098, 984; and any mixtures of the foregoing. Typical antioxidants include hindered phenols such as triethylene glycol bis (3- (3'-third butyl-4'-hydroxy-5'-methylphenyl) propionate, N, N'-hexamethylene Bis (3,5-tert-butyl-4-hydroxyhydrocinnamide) and mixtures thereof and the antioxidants disclosed in U.S.P. 4,9 7 2,0 1 4. Combinations described herein Materials can be prepared by methods known in the art by mixing all ingredients and the acetal polymer at a temperature above the melting point of the shrink polymer.

Page 11 483919 V. Description of the invention (9) It is known that powerful mixing devices such as rubber mills, internal mixers such as "Banbury " and " Brabender n mixers " Single or multi-blade internal mixer \ co-kneader for external heating or friction heating of holes ", multi-blade mixers such as π Farrel continuous mixer π, injection molding machine and single-shaft and double-shaft extruder, co-rotation And reversed square turn to prepare a thermoplastic polyacetal composition. These devices can be used alone or in combination with electrostatic mixers, hybrid eddy current machines and / or various devices' to increase internal pressure and / or mixing strength of valves, gates or shafts as designed for this purpose. An extruder is preferred, and a biaxial extruder is most preferred. Of course, 'this mixing needs to be performed at a temperature lower than that at which the polyacetal will degrade significantly. The polyacetal composition is usually melt-processed at 170 to 290 ° C, preferably 185 to 240 ° C, and most preferably 195 to 25 ° C. The present invention can be formed into shaped articles using methods known in the art, including compression molding, injection molding, extrusion, blow molding, rotary molding, melt spinning, and thermoforming. It is better to use injection molding. Examples of molded objects include sheets, contours, rods, films, monofilaments, fibers, leather cords, tapes, tubes, and conduits. Such shaped articles can be post-processed by orientation, stretching, cladding, quenching, coating, laminating, and electroplating. Such shaped articles and their fragments can be ground and re-molded. Those skilled in the art will understand that various modifications and substitutions can be made to the above-mentioned invention without departing from the spirit and scope of the invention. Accordingly, it should be understood that the present invention will be exemplified but not intended to limit the present invention. Experiments The following tests were performed using the ECHIP Industry

Page 12 V. Description of the Invention (ίο)-1P ’’ experimental design software setup. This design experiment includes repeated runs that can count + estimate errors. Because this is a design experiment, it is not possible to compare pairs of experiments with only “variable variables. Instead, you need to rely on statistical analysis of the result insertion method. Use acetate-terminated water with a weight average molecular weight of 72,000 Samples were prepared. The samples listed in the table were obtained using a 40-meter biaxial extrusion mechanism of Werner and Pfleiderer. A 50-pound sample was produced at 200 per hour. The machine is performed at 2 25-400 rpm and the barrel temperature is set at 20 0-2 25 ° C. Samples containing P561 wax but not EMA are difficult to perform because wax will interfere with the melting of POM, so higher temperatures and temperatures are required. Machine speed. EMA is EMAC® SP2 2 0 5 from Chevron Chemical Company, which is a copolymer of 80% ethylene and 20% methyl acrylate with a melt index of 2 g / 10 minutes. P5 61 is Moore and Munger Non-polar hydrocarbon soil sold. Celcon® U-10 is a branched acetal trimer made by Hoeschst-Celanese (now Ticona). Ultratalc® 6 0 9 is talc supplied by Barretts mining industry. Zemid® 6 4 1 is 40% talc in polyethylene supplied by DuPont. U-Talc 609 / EM A is the 40% dispersion of Ultratalc in EMA. 11-Ding 3 0 6 0 9 kg 5 61 is 1111 ^ 3 7 31 (: 1) 5 61 40% dispersion 0

Page 13 483919 V. Description of the invention (π) Table 1 Composition number ΕΜΑ% P561% U-Talc% U-Talc source DSC crystal Tl / 2 158C (minutes) Crystallization time in the mold (shirt,) 1 0 0 0 ZEMID 641 2.9 6.7 2 3 L5 0 ZEMID 641 3.28 73 3 0 L5 0.08 ZEMID 641 2.18 6.5 4 3 1.5 0 U-TALC 609 jj 1 6.9 5 3 0 0.08 U-TALC 609 / P561 2.39 5.6 6 0 1.5 0.08 U-TALC 609 / P561 2.12 6.8 7 0 0 0.08 U-TALC 609 1.96 5.9 8 3 0 0 U-TALC 609 / EMA 7.2 7 9 0 1.5 0.08 U-TALC 609 / EMA 2.03 6.3 10 3 1.5 0 U-TALC 609 / P561 13.43 7.2 11 3 0 0.08 U-TALC 609 2.14 5.8 12 3 0 0.08 ZEMID 641 2.74 5.6 13 0 1.5 0 U-TALC 609 8.42 6.4 14 0 0 0 U-TALC 609 / P561 3.26 7 15 3 1.5 0.08 U-TALC 609 / EMA 2.26 6.1 16 0 0 0 U-TALC 609 / EMA 10.47 6.8 17 1.5 0.75 0.04 ZEMID 641 2.87 6.6 18 1.5 0.75 0.04 U-TALC 609 1.75 5.5 19 1.5 0.75 0.04 U-TALC 609 / P561 6.24 5.7 20 1.5 0.75 0.04 U -TALC 609 / EMA 5.74 5.8 21 0 0 0 ZEMID 641 3.69 6.3 22 3 1.5 0 U-TALC 609 3.25 6.9 23 3 0 0.08 U-TALC 609 / P561 2.43 5.5 24 3 0 0 U-TALC 609 / EMA 7.94 6.6 Ι II. Page 14 483919 V. Description of the invention (12) Use a differential scanning card meter (DSC) to measure half the time of crystallization. 10 grams of resin was heated in Perkin-Elmer DSC 7 at 50 ° C / min to 21 ° C for 3 minutes, and then quickly cooled to 200 ° C crystallization temperature at 200 t / min, and held at that temperature until Crystallization is complete. It takes half the time to crystallize from the position of the exothermic peak of the crystal. The melting time curve graph during the ix 8 X 0.0 7 inch bar formed from the injection mill of the sample is used to obtain the crystallization time in the mold. Then, use Echi〆 software for statistical analysis The effect of DSC and the number of crystals EMA and P 561 wax in the mold measured by these substances is illustrated. Note that in the presence of /, '/ month a horse owner's square 4 agent, usually has a slowing effect of crystallization ( D one person plus) of the "Zemid" wax now has an adverse effect, which increases the time at which t increases the time at which the crystallization time is reduced by half at 158 t). Day-to-day V rate (DSC samples also pay attention to review the data in Table 2 below to show EMA 0 8%。 Θ 、、。 Compared to nucleation, the effect of crystallization is small, and it has only a small effect on the crystallization.

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V. Explanation of the invention (13) Table 2_ Examples of average data EMA% P561% Talc% Average crystallization time (seconds) — 1 0 0 0 ------— 6.7 2 3 0 0 ________ ^ 6.8 3 0 1.5 0 6.4 4 3 1.5 0 _______ ------- 7.1 5 0 0 0.08 5.9 6 3 0 0.08 5.8 7 0 1.5 0.08 6.8 8 1.5 0.75 0.04 5.7 9 1.5 0.75 l% Celcon U10 5.6 Polyvariable acid contains variable ΕΜ A and P A plot of half the time of crystallization in the 5 6 1 composition is shown in Figure 1a. Figure 1b shows a half-time graph of the crystallization of a polyacetal composition containing 0. 080% nucleating agent (z em 丨 d) and a variable amount of EMA and P 561. By injection molding a sample containing the polyoxymethylene resin and the additives shown in Table 3 below to form a rod-like object, the period of the non-nucleated resin is too short to produce non-porous parts. This rod was cut longitudinally to analyze its internal structure. Cut

Page 16 483919 V. Photocopy of the rod of the invention description (14) is shown in Figures 2a, 2b and 2c. It can be seen that in comparison of rods 2b and 2c which do not contain the three additives used in the present invention, sample 1 (FIG. 2a) of the example of the present invention is substantially free of pores. Table 3 Nucleating agent /% EMA {PE wax 1. Celcon U-10 * / 2% 1.5% .75% 2. 0.17Zemid® contains 0.08% talc 0 0 3. 0 0 0 * mw of branched trimer = 109,000 The additives shown in Table 4 below were mixed together in a 40 mm W & P twin-shaft broadcaster and then molded into a 1/4 inch thick tension rod, unmodified control resin # 3. The molding cycle is too short. The rods were then machine-processed 1/8 inch thick to analyze internal porosity. Note that control sample # 3 has many pores and sample 14 of the present invention is very small. The latter is even more desirable for molding applications.

Page 17 483919 V. Description of the invention (15) Table 4 Tests Acetal MW Additive Branched trimer MW = 109,000 3 85000 Yiwu 6 85000 ΕΜΑ / 2, P561 / · 4 No 12 85000 1 14 85000 ΕΜΑ / 2 Photographs of P561 / · 4 1 machined to reveal the internal porosity of rods are reproduced in Figures 3a, 3b and 4a and 4b. Figure 3a corresponds to Sample 3 of Table 4; Figure 3b corresponds to Sample 6 of Table 4; Figure 4a corresponds to Sample 12 of Table 4; and Figure 4b corresponds to Sample 14 of Table 4.

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Claims (1)

483919 Gongfeng Carcinoma: A 8810 Lion Amendment VI. Application for Patent Scope Wx, 1. A polyisocyanate composition comprising: a) polyacetal polymer; b) 0.5 to 3% by weight of polybutane / Unsaturated carboxylic alkane ester polymerized nucleating material, which comprises a copolymer or terpolymer of a low carbon number alkane (C2-C4) and a low carbon number burnt ester of an unsaturated acid. c) 0.1 to 1% by weight of a waxy denucleating substance; and d) 0.01 to 3% by weight of a nucleating agent, wherein the nucleating agent is a nitrided tent, talc, silicon oxide, polyfluorene Imine, branched or cross-linked acetal copolymer or terpolymer, melamine-formaldehyde resin, calcium carbonate, diatomaceous earth, dolomite or encapsulating nucleating agent including encapsulating polymer and nucleating agent . 2. The composition according to item 1 of the scope of patent application, wherein polyoxal is a homopolymer of pyraldehyde or a cyclic polymer of pyraldehyde, and its end group is terminated by esterification or etherification; or Or copolymer of aldehyde formaldehyde cyclic polymer and other monomers which can generate oxyalkylene group with at least two adjacent carbon atoms in the main chain, the end group of the copolymer can be hydroxyl end or can be esterified Or etherified caps. 3. The composition according to item 1 of the scope of patent application, wherein the unsaturated carboxylic acid low-carbon alkyl ester is an unsaturated carboxylic acid alkyl ester containing 3 to 8 carbon atoms. 4. The composition according to item 1 of the scope of the patent application, wherein the unsaturated carboxylic acid with a low carbon number is intended to be acrylic acid, acrylic acid, acrylic acid, acrylic acid, acrylic acid, isopropyl acid, or acrylic acid. N-butyl S purpose, fluorenyl acrylate S purpose, fluorenyl acrylate, propyl acrylate, isopropyl methacrylate, n-butyl methacrylate, and isobutyl methacrylate. 5. The composition according to item 1 of the patent application scope, wherein the nucleating agent is a fine-grained solid. O: \ 56 \ 56383.PTC Page 1 2001.08.06. 020 483919 Amendment _ Case No. 88100066 6. Scope of patent application 6. —A kind of molded article, including: a) polyacetal polymer; b) polyendeline / Unsaturated carboxylic acid low-carbon alkyl ester polymerized nucleating substance; c) waxy denucleating substance; and d) nucleating agent. 7 · A method for preparing a polyacetal composition as described in claim 1 in the scope of patent application, comprising: a) preparing a polyacetal polymer component; b). Melt blending step a) the polyacetal polymer prepared And i) poly (arylene / unsaturated carboxylic acid low-carbon alkyl ester) polymerized nucleating substance; ii) waxy denucleating substance; and iii) composition of nucleating agent. O: \ 56 \ 56383.PTC Page 2 2001.08.06. 021